improving body weight exercises

I think weighted push up if done as heavy as bench press, are even more dangerous than bench press, since your shoulder can move around freely instead of having a stable base to push from. But also for that reason, if you are not doing any dangerous weight you are less likely do develop long term shoulder issues compare to bench press (all stabilizing muscle are developed more equally, while bench pressing might let you pushing more than what your shoulder is capable of). If you want to take it up one notch with shoulder health, consider doing hanging rings exercises - your shoulder girdle will be bullet proof for years of strength to come.

well i will not go very heavy in push ups , i would not place any weight more than 20 pounds plate in my back

Best for what?
If it's for shoulder strength, the front support position (or dips to front support) is killer.
If it's for bulging chest development, then it's hanging rings fly

Ring Fly Aways

i will try them , they do look effective

Umm, would be good idea to add some inverted rows also.
Currenlty the push-pull ratio is 2:1

Just for balance, then you are doing: Horizontal push and pull, vertical pull and push.

Ratio 2:2

Im just sayin....

Weighted pushups done with an appropriate weight (if that appropriate weight for you is 200-400 extra pounds, okay) I don't see as inherently dangerous or remotely as dangerous as a heavy bench press. You seem to be trying to equate stability to safety, in which case leg press would be much safer than a squat and SO much safer than a single leg squat if done with a heavy load.

Then you're trying to say that rings are superior for shoulder health?

I see where you're coming from with all of this but I think a lot of it is trying to relate things that simply aren't inherently correlated and using a kind of general logic. Rings are great for many purposes, king of these natural ROM and the great tension and activation they often illicit but we're comparing apples to oranges and saying one's better than the other because of the color of the skin and then mentioning how great pears are. Just doesn't quite follow.

Weighted pushups(with a pushup plus at the end), chin ups where you depress your scapula from the mid-point until the maximum amount at the end of the concentric and get your chest to the bar and endless rowing are a great combo for shoulder health and safety.

The plus at the end of the pushup is REALLY important, so is keeping neutral spine and tucking your elbows and not letting them flare. Otherwise you're really beating on your shoulders, checkout this article.
http://www.t-nation.com/free_online_article/most_recent/the_best_damn_pushups_article_period

Chin ups are best done for health in a neutral grip (or on rings) and depressing your scapula is critical for stabilizer development and health.

Rowing is the most important thing you can possibly be doing if you have any concern for shoulder health. Doing more rowing than pressing is never a bad idea. Just make sure you are retracting the scapula as much as possible the whole movement, and at the end of every rep (end of the eccentric) let your shoulder(s) protract for maximum ROM and to avoid rhomboid dominance. Also be sure to depress your scapula as much as possible from the mid point of the concentric onward, think of it as trying to put your shoulder blade in your opposite back pocket(s).

All of these can be done with bodyweight, and bodyweight+added weight. TRX or ring pushups should be great for health AND for making your chest grow (showed really high activation levels when tested) but I've seen fine results with chest growth doing your normal everyday weighted pushups.

Yes, chinups and inverted rows from rings, straps, TRX...are easier on the joints, because you can naturally rotate the wrists throughout the motion.